DE2455846A1 - Catalyst for the ammoxidn. of propylene/isobutylene - to (meth)acrylonitrile, used as a fluidised bed - Google Patents

Abstract

(Meth)acrylonitrile is produced by reacting propylene or isobutylene with oxygen and ammonia at 300-600 degrees, pref. 350-480 degrees C, and at 1-10 atm. in a fluidised bed of a catalyst of formula: Fe1-5 and/or Al1-5Bi1Mo10-20X0.1-2E1-20On-A0.1-1 (where X is P and/or As; E is >=1 Gp. II element and/or Mn; A is an alkali metal and n depends on the valency of the remaining elements) in which the atomic ratios Bi:Mo, Fe/Al:Bi and Fe/Al:Mo are 1:10-20.1-5:1 and 1:3-5 resp., this catalyst opt. being supported. The catalyst is mechanically strong enough to operate as a fluidised bed, has a high efficiency and produces a high degree of olefin conversion with low by-prodt. (esp. acetonitrile and HCN) formation. Very high conversion w.r.t. ammonia is obtd.

Description

Process for the production of acrylonitrile or methacrylonitrile The invention relates to a catalytic process for the production of acrylonitrile or methacrylonitrile by reacting propylene or isobutylene with oxygen and ammonia.

It is well known that by reacting aliphatic olefins, which contain 3 or 4 carbon atoms, with xuft or oxygen and with ammonia on catalysts i, ß - to produce unsaturated aliphatic nitriles. The implementation is generally carried out in Temperatures of 300 to 500 ° G and pressures of 1 to 10 at, preferably 1 to 5 at. In this respect, there are hardly any differences between the known processes. Considerable differences between the procedures result from a very great variety of catalysts, which are distinguished both by their composition as also differ by their method of manufacture and one of the individual processes exercising a distinctive and characterizing flow of influence, which determines their Is profitability.

Due to the high sales volumes, it is of crucial importance in what percentages the acrylonitrile and the hard-to-use acetonitrile arise and whether the by-product hydrogen cyanide should be isolated or destroyed will. Properties of the catalyst such as abrasion, Lifespan, The ability to work up the used catalyst is undesirable during the manufacturing process a significant polymerization of the reaction products, which leads to deposits in the Apparatus leads.

For the production of unsaturated nitriles there are a large number of Known catalysts.

So it is known to produce antimony catalysts that also still other metals, e.g. molybdenum, bismuth, iron, lead or tin and partially contain other metals.

A number of other catalysts do not contain antimony.

So catalysts are known that iron, nickel and cobalt, others the molybdenum, phosphorus, iron, cobalt, and nickel and those containing molybdenum, bismuth and contain phosphorus. Taking into account all demands that are placed on you economically working catalyst are provided, those have proven to be the most favorable which contain molybdenum, bismuth, phosphorus, iron and possibly other elements.

Thus a catalyst is known which has the general composition m Fe2O3.n Bi2O3.o Mo O3.p P2O5.q SiO2, where m and n have the values 0.1 to 4, p can assume the values 0 to 0.3 and q the values 0 to 2 if 0 = 2.

Another reference describes a catalyst that consists of the same oxides in an atomic ratio of Feib to 10 Bi1 to 10 1 to 10 P0.03 to 3 consists.

It is also known to use these oxides in a ratio of 6 to 26% by weight bismuth, 2 to 20% by weight molybdenum, 0.5 to 10% by weight iron and optionally 0.1 to 1.0% by weight of phosphorus to be used.

It is also known to contain the oxides in an atomic ratio of 5 to 15 Bi1 to 10 Mo15 P0.03 should be used, the 2 BET surface area being 4 to 30 m2 / g and where this surface area is inversely proportional to the iron content stands. In other references, catalysts are described which except Mo, Bi, P and Pe contain other elements.

A catalyst is known which contains the elements Mo, Bi, P, Fe, Co and Na and / or K in an atomic ratio of 12: 1 to 11: 1 to 9: 1 to S: 0.5 to 2 each 12 Contains molybdenum atoms, the sum of bismuth and cobalt atoms being 6 to 12.

Finally, it is known to use a catalyst which has the Formula A Bb C Fed Bie Mof ° x, where A corresponds to at least one element from the Group consisting of the alkali metals, the rare earth metals, tantalum and Niobium, B is Xobalt and / or nickel and C is phosphorus and / or arsenic and a and c is a number from 0 to 3, b is a number from 0, 1 to 20, d is a number from 0.1 to 8, e is a number from 0.1 to 6, f is a number 8 to 16 and x is a number that changes results from the weights of the other elements. Preferably A is potassium, samarium or tantalum. The alkali metal is incorporated into the catalyst prior to calcination, whereupon it converts to the oxide.

The known catalysts have one or more of the following Disadvantages on. The mechanical strength is often so low that during use of the catalyst in the vortex process, too much abrasion occurs, which then results in the apparatus deposits in undesirable places.

Parts of the reaction products polymerize and form deposits in the apparatus. Sometimes the yields of acrylonitrile are too low and of the poorly usable by-product acetonitrile too high.

The purpose of the invention is a process for the production of acrylic acid ethyl or itethacrylic acid nitrile by reacting propylene or isobutylene with oxygen and ammonia in the absence of catalysts, which is characterized by a low catalyst requirement with almost complete conversion of the unsaturated hydrocarbon with high space velocity over the catalyst, due to a high yield of nitrile and low by-product formation Acetonitrile and hydrocyanic acid as well as an extensive conversion of NH3, what has a positive effect on the post-processing of the deaeration products.

The object of the invention is to provide the method for production of methacrylic acid nitrile or methacrylic acid nitrile by converting propylene or Isobutylene with oxygen and ammonia at temperatures from 300 to 600 ° C, preferably to carry out from 350 to 480 OC, and at pressures of 1 to 10'at on catalysts, According to the invention, this object is achieved in that the reaction takes place in a fluidized bed is carried out on catalysts that have the general formula Fe1bis 5 and / or Al1 to 5 Bi1 Mo10 to 20 X0.1 to 2 E1 to 20 A0.01 to 1 On, where X phosphorus and / or arsenic, E one or more 2nd group elements of the periodic table and / or manganese and A are alkali metals, in which the atomic ratios-Bi : o 1:10 to 1:20 be / hl: Bi 1: 1 to 5; 1 and Be / Al: Mo 1: 3 to 1: 5 and where n results from the valence of the other elements, where these catalytically active oxides can be applied to a carrier.

As elements of the see group of the periodic table are particularly suitable Magnesium and / or cadmium.

Potassium is preferably used as the alkali metal.

The effective combination can be used on a carrier which is known, such as kieselguhr, pumice stone, l'onerde, kaolin or advantageously Silica gel obtained from an aqueous sol.

The proportion of this carrier is generally between 20 and 80, preferably between 40 and 60% by weight.

The catalyst used in the present invention can be easily obtained from a sweetening of the corresponding oxides in suitable proportions. All substances and compounds of the elements mentioned can be used can be converted into the oxides of these elements according to known processes.

The catalysts are activated by heating the oxide mixture with and without carrier or when using 'connections of the elements mentioned, which is in the oxides let it pass over by calcining in one go Temperature range between 280 ° and 800 OC, preferably between 5500 and 700 00.

The annealing times should be between 30 minutes and 24 hours and the surface of the catalyst between 5 and 70 m 2 / g, preferably between 20 and 40 m 2 / g. An addition of sulfuric acid or sulphates to the catalyst before glazing or calcining increases the activity of the catalyst.

A special preparation of the catalyst according to the invention with high activity is based on the following: 1. Production of an aqueous ammonia-containing Solution or suspension with molybdenum oxide, molybdenum oxide hydrate or ammonium molybdate (NH4) 6 Mo7O24 .4 H20 in claimed proportions with the addition of the appropriate Batch of phosphoric acid or phosphorus pentoxide or arsenic oxide (As 203) 2. Manufacture of nitric acid solutions or suspensions of the other elements and components, e.g. from their metals, oxides, carbonates or nitrates, in appropriate proportions individually or in a mixture.

3. When using carriers, e.g. SiO2, a Aqueous silica sol used in the appropriate quantitative ratio or the carrier introduced into the solution under 1 or 2 or soaked with the solutions.

The solutions or suspensions under 1, 2 and 3 are added with stirring at temperatures below 80,000, preferably below 50,000, in any order united. The mixture of substances obtained is dried in a known manner, either through embrittlement or evaporation, and calcined.

The ammoxidation of the olefin is generally carried out under known conditions carried out.

The gas mixture olefin, oxygen or air and ammonia, which is about the catalyst is passed, can in its quantitative ratio in a wide range can be varied.

The volume fractions. are preferably included. Olefins and ammonia between 1 and 15, for oxygen between 2 and 14 percent.

The rest consists of one or more inert gases, such as nitrogen, saturated hydrocarbons such as propane or water vapor. Advantageously one can use air, a mixture of air and an inert gas as the diluent.

The reaction of olefin, ammonia and oxygen is between 300 and 600 00, preferably between 350 and 480 ° C. The dwell time should be between 0.1 and 20 seconds.

The following examples are intended to explain the invention in more detail: There were fluidized bed catalysts with Si02 according to the production method described above produced as a carrier with the following composition: Example 1 6.6 kg of a silica sol with a silica content of 30% by weight are mixed with 48 g of 80% aqueous phosphoric acid mixed. For this purpose, a solution of 1.31 kg of molybdenum oxide (94%) in 3.65 1 water and 0.77 1 ammonium hydroxide (24%) are added (solution 1) beforehand 160 g bismuth dissolved in 460 ml nitric acid (45%), plus 1.37 kg Mg (NO3) 2. 6th H20, 940 g Fe (NO3) 3 9 1120, 7.73 g of KNO3 and 1.95 g of NaNO3 were added and diluted with 2.5 l of water (solution 2) The solution 2 becomes the prepared solution 1 given, the solutions mixed well and dried by spraying. The spray product obtained in this way is then 50 minutes at 620 ° C. in a stream of air heated.

Bi1 Fe3 Mg7 Mo11.2 P0.5 K0.1 Na0.03 Si43 Example 2 6.6 kg of a Silicic acid sol (30% SiO2) are mixed with 48 g of 80% phosphoric acid and added an ammoniacal molybdenum solution containing 1.75 kg of molybdenum oxide (94%) contains dissolved in 3.65 1 water and 1.03 1 NH4OH (24%) (solution 1) 160 g bismuth dissolved in 460 ml nitric acid (45%), the excess nitric acid evaporated, diluted with 2.5 l of water and in it 685 g of Mg (NO 3) 2 6 H 2 O, 770 g of Mn (NO3) 2. 6 H2O, 940 g Fe (NO3) 3. 9 H2O and 7.73 g KN03 dissolved.

(Solution 2) The solution 2 is added to the prepared solution 1, the solutions are mixed with one another and the mixture of substances is dried by spraying. The spray product obtained is then calcined for 50 minutes at 620 ° C. in a stream of air.

Bi1 Fe3 Mg3.5 Mn3.5 Mo15 P0.5 Si43 K0.1 3eisiel 3 6.6 kg of a silica sol (30 Voig) are mixed with 48 g of 80% phosphoric acid. This is done with stirring a solution of 1.17 kg of molybdenum oxide (94%) in 3.65 l of water and 0.77 1 NH4OH (24% strength).

A solution containing 375 g of Bi (NO3) 3. 5 H2O, 540 g Cd (NO3) 2. 4 H2O, 940 g Fe (NO3) 3. 9 H2O, 7.73 g KNO3 and 1.95 g NaHO3 contains the mixture of substances dissolved in 2.0 l of water and 100 ml of nitric acid (45%) dried by spraying and the spray product obtained in this way at 620 for 50 min ° C annealed in a stream of air.

Bi1 Fe3 Cd2.5 Mo10 P0.5 K0.1 Na0.03 Si43 Example 4 To a solution of 152 kg molybdenum oxide (94%) in 3.6 1 water, 0.77 1 NH4OH (24%) and 48 g 80 of a phosphoric acid, a solution of 375 g of bi (NO3) 3.5 H20, 485 g Mg (NO3) 2.6 H2O, 995 g Mn (NO3) 2. 6 H2O, 940 g Fe (NO3) 3. 9 H2O and 7.73 g KNO3 in 1.2 l of water, 100 ml of nitric acid (45%) and 22.5 g of sulfuric acid were added.

The substance mixture is mixed with 6.6 kg of a silica sol (30 J SiO2) mixed and dried by spraying.

The spray product obtained is then 50 minutes at 620 from im Annealed air stream.

Bi1 Fe3 Mg2.5 Mn4.5 Mo13 P0.5 K0.1 Si43 (SO4) 0.3 Example 5 In the following the active components are placed on a preformed carrier (SiO2 with medium particle size 0.04 to 0.08 mm) applied by impregnation.

3000 g of a pre-formed, powdery silica gel are accordingly the previously determined pore volume of 2600 g an aqueous ammonium molybdenum solution (760 g MoO3) and 29.6 g 80% phosphoric acid. First is at temperatures by 120 of the water contained in the catalyst slowly evaporated. Then it takes place the gradual decomposition of ammonium molybdate to molybdenum oxide at 300 ° C.

It is then soaked with 1.9 l of a nitrate solution that is 99.4 g Bi, 106 g g Fe, 40.3 g Lfg, 91 g Mn and 4.45 g K in solution, again at Dried at 120 C and annealed for 45 minutes at 620 oC in a stream of air.

Bi1 Fe4 Mg3.5 Mn3.5 P0.5 Mo11.2 K0.24 Si105 Example 6 6.6 kg of a Silica sols with a silica content of 30% become 80% aqueous with 48 g Phosphoric acid mixed.

A solution of 1.31 kg of molybdenum oxide (94 %) in 3.65 1 water and 0.77 1 ammonium hydroxide (24%) added (solution 1) Before doing this, 160 g of bismuth are dissolved in 0.5 l of nitric acid (50%), plus 545 g of Mn (NO3) 2. 6 H2O, 885 g Mg (NO3) 2. 6 H2O, 470 g Fe (NO3) 3. 9 H2O, .427 g Al (NO3) 3. 9 H2O, 7.73 g KNO3 and 1.95 g NaN03 are added and diluted with 1.5 liters of water (sol. 2) The solution 2 is added to the prepared solution 1, the solutions together mixed and dried by spraying.

The spray product obtained is then im Annealed air stream.

Bi Fe1.5 Mg4.5 Mn2.5 P0.5 K0.1 Na0.03 Mo11.2 Si43 Al1.5 example 7 6.6 kg of a silica sol are mixed with 48 g of 80% phosphoric acid and a solution of 1.64 kg of molybdenum oxide (94%) in 4.2 l of water with stirring and 0.97 l ammonium hydroxide (24%) are added (solution 1) 160 g bismuth are added beforehand Dissolved in 0.5 1 nitric acid (50%), plus 545 g Mn (NO3) 2. 6 H20, 885 g Mg (NO3) 2. 6 H20, 855 g Al (NO3) 3. 9 B20, 7.73 g KN03 and 1.95 g NaNO3 and with 1.5 1 diluted water (solution 2) The solution 2 is added to the prepared solution 1, the solutions mixed together and dried by spraying.

The spray product obtained is then immersed for 60 minutes at 550.degree Annealed air stream.

Bi Al3 Mg4.5 Mn2.5 P0.5 K0.1 Na0.03 Mo14 Si43 Tabel 1 Catalytic test results of the catalysts produced according to Examples 1 to 7 Selectivities in mole percent propylene ACN AN HON Example 1 80 1.5 6 Example 2 79.5 1.5 4 Example 3 78 2 8 Example 4 81 1 4 Example 5 78 1.5 3 Example 6 74.5 3.0 3 Example 7 70 8 3.5 Reaction temperature: 430 ° C. Gas ratio: C3H6: NH3 : Air = 1: 1: 10 ACN: Acrylonitrile AN: Acetonitrile HCN: Hydrocyanic acid C3H6: Propylene N113: ammonia

Claims (7)

Claims 1. Process for the production of acrylonitrile or methacrylic acid nitrile by reacting propylene or isobutylene with oxygen and ammonia in the presence of catalysts at temperatures from 300 to 600 00, preferably from 350 ° to 480 OC, and at pressures from 1 to 10 at, characterized in, that the reaction in the fluidized bed is carried out on such catalysts that the general formula Fe1 to 5 and / or Al1 to 5 Bi1 Mo10 to 20 X0.1 to 2 E1 to 20 ° n corresponds to A0, 1 to 1, where X is phosphorus and / or arsenic, E is one or more Elements of group 2 of the periodic table and / or manganese and A denote alkali metals, where the atomic ratios Bi: i \ 'io 1:10 to 1:20 Fe / Al: Bi 1: 1 to 5: 1 and Fe / Al: Mo 1: 3 to 1: 5 and where n is derived from the valency of remaining elements results, these catalytically active oxides on a support can be applied. 2. The method according to claim 1, characterized in that as an element the 2nd group magnesium is used. 3. The method according to claim 1, characterized in that as an element of the 2nd group cadmium is used. 4. The method according to claim 1 to 3, characterized in that as Element of the 2nd group Iuliagnesium and Cadmium can be used in a mixture. 5. The method according to claim 1 to 4, characterized in that as Alkali metals potassium and / or sodium is used. 6. The method according to claim 1 to 5, characterized in that the Catalyst mixture before annealing or calcining sulfuric acid or sulfates be admitted. 7. The method according to claim 1 to 6, characterized in that the Oxides on kieselguhr, pumice stone, clay, kaolin or preferably on a silica gel are applied as a carrier.